The Yamaha RD400F Daytona Special was the last hurrah of a
long line of sporty midsized 2-strokes. Although Yamaha intended the Daytona to
commemorate its racing successes of the previous year, this bike ended up as a
monument to the 2-stoke motorcycles that defined an era. The Daytona Special
was the last air-cooled street 2-stroke sold in the United States.

Once upon a time, the streets were full of inexpensive
2-stroke motorcycles. Mostly made in Japan, people either loved or hated
these bikes. On the plus side, they were cheap to buy, generally easy to
maintain, and typically went like stink. On the minus side, they fouled the
air, made an offensive racket and often frightened people thanks to their noise
and peaky power. Early ones had suspect handling and subpar brakes, but by the
early Seventies the handling had improved and the brakes actually stopped the
bike.

In 1973 Yamaha introduced the RD350, a 347cc 2-stroke twin
that was loosely based on the then very successful Yamaha production racers.
Carry-overs from the racers included the double cradle frame and much of the
2-stroke engine. Upgrades over prior Yamahas included a reed valve induction
system and a front disc brake.

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The Yamaha RD400F Daytona Special was the last hurrah of a long line of sporty midsized 2-strokes.Photo By Nick Cedar

The RD400F’s slim profile and a wet weight of just more than 370 pounds made it a natural on twisty roads and racetracks.Photo By Nick Cedar

The forks were an inch longer than on the RD350 and were fitted with Teflon bushings to cut down friction. A large airbox dampened the 2-stroke noise.Photo By Nick Cedar

The shrouded cylinder head aided in cooling.Photo By Nick Cedar

Contemporary testers agreed that the RD400 was an improvement on the RD350 and fun to ride.Photo By Nick Cedar

In honor of Yamaha’s wins at Daytona and other AMA races, for 1979 the RD400F was named the Daytona Special.Photo By Nick Cedar

By 1979, U.S. emissions standards had grown increasingly more stringent, but the Daytona Special met them.Photo By Nick Cedar

Two-stroke enthusiasts jeered at Yamaha, swore at the EPA and kept riding their anti-social, noisy and fun motorcycles.Photo By Nick Cedar

The RD400F sported a host of improvements over the 350, including a larger fuel tank, a lower seat height and a bump in compression.Photo By Nick Cedar

The tail cowl continues the red stripe that runs down the front fender and tank.Photo By Nick Cedar

Yamaha engineers incorporated some interesting ideas into
the powerplant, such as a small seventh port in the RD350’s induction system
that fed directly from the carburetor manifold. The port provided an extra shot
of fuel and air for improved combustion chamber filling and scavenging, and
cooled the piston crown. As a result of the induction system — along with a
well-supported, low friction crankshaft and a 6-speed transmission, the RD
boasted a relatively wide powerband and a top speed just shy of 100mph. Most
2-strokes had powerbands the width of a guitar string, so the RD350 was a
significant advance, making the RD a very civilized ride. The reed valve system
also improved the gas mileage, another plus as 2-strokes were often very
thirsty.

The RD350, although better than most of what was available,
was not perfect. The front wheel had a tendency to become airborne under hard
acceleration, the seat was uncomfortable after a few miles, and the oil tank
leaked. But perfection was not required by the hordes of young RD fans — just
speed, handling, acceleration and an affordable price, all of which the RD
could deliver. Sales of RDs were brisk, and many turned up at local racetracks.

Former Cycle Guide editor Dain Gingerelli remembers
that two kinds of riders bought RDs — aspiring canyon carvers and what Cycle
Guide staffers called “white punks on RDs. You’d see them at the beach,
dressed in a Shoei helmet, tennis shoes, jeans and T-shirts. Sort of a surfer
on wheels, if that makes sense,” Gingerelli remembers.

Yamaha was aware, however, that impending emissions and
noise regulations would make sales of 2-strokes more difficult. Its response
was twofold. First, the company invested significant time and resources into
developing a new line of 4-stroke engines. Second, it researched lessening
emissions from its existing 2-stroke lineup.

Yamaha introduced the RD400, a stroked and refined evolution
of the RD350, in late 1975. The RD400 featured a redesigned clutch hub and
different transmission gear ratios to complement the engine’s powerband. Yamaha
engineers improved the porting and added a bypass hole that ran at a 45-degree
angle directly to the exhaust passage. This hole eased starting, reduced low
rpm surging and quieted the exhaust note at low speed. A longer reach spark
plug reduced the tendency of the RD to eat plugs. The carburetors were new, and
the battery and coil ignition system was beefed up to cope with brighter
lights. The frame was basically the same, but the powertrain was now mounted in
vibration-stopping rubber bushings, and the wheels were seven-spoked mags, both
fitted with disc brakes. The forks were an inch longer than on the RD350 and
were fitted with Teflon bushings to cut down friction. A large airbox dampened
the 2-stroke noise.

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The engineers also added features to improve reliability and
ease maintenance, including dual taillight bulbs, extra fuses, and a means to
easily synch the two carbs and oil pump. Additionally, the engine was moved
forward in the frame to curb the bike’s tendency to wheelie on takeoff.

Contemporary testers agreed that the RD400 was an
improvement on the RD350 and fun to ride. “You can’t help but love it,” Cycle
World proclaimed in a gush of enthusiasm. The road test concluded that it
was the closest thing the magazine had ever seen to a perfect motorcycle. In fact,
the only real complaint the testers had was that the horn wasn’t loud enough.

Other magazines pointed out that despite engine mounting
improvements, too much weight aft and a little extra throttle would cause the
front wheel to lift, and the front brake was strong enough it could lock the
wheel during panic stops.

Cycle was known for its comparison tests during the
Cook Neilson era, and the August 1976 issue featured a shoot-out between seven
Japanese models conducted during a five day tour around Southern
California. In addition to Cycle staffers, the riding party
included Marty Dickerson, Bonneville record holder on a Vincent and still an
active Vincent enthusiast today.

The Yamaha came in fourth out of seven. Despite praise for
its speed, excellent handling, and low price, the bike’s lack of suitability
for touring and mediocre ergonomics dropped it to mid-pack. That said, the
RD400 was a clear winner in the twisties, even though much of the crew felt it
was an expert’s bike that required saddle time to master. Quick steering,
grabby brakes and a short wheelbase demanded rider concentration going down a
twisty road at speed.

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The RD400 was as popular as the RD350, and Yamaha sold a lot
of them. Eddie Lawson and a host of lesser-known GP racers got their start
racing RDs, as did some motorcycle journalists, including Buzz Kanter and Dain
Gingerelli. Gingerelli thinks his success racing RDs was a factor in his being
hired by Cycle Guide.

The next few years were spent in detail improvements,
including self-canceling turn signals and a more harmonious paint scheme. Small
improvements to the engine improved both top speed and fuel economy. By 1978,
the Yamaha twin was the last 2-stroke road bike on the U.S. market.
While all the other major manufacturers had abandoned 2-strokes for four (on
the street, anyway) Yamaha soldiered on with its still popular and still fast
twin, which not only sported 2-stroke power but cemented its status as a bike
for real motorcyclists with kickstart-only ignition.

The Yamaha RD400F Daytona Special

In 1979, Yamaha looked back at the past few years of its
dominance in road racing and decided to commemorate its racing stars. Kenny
Roberts and Mike Baldwin were then dominating Daytona and AMA racing in
general. In honor of their efforts, the last iteration of the 2-stroke twin,
the RD400F, was named the Daytona Special.

By 1979, U.S.
emissions standards had grown increasingly more stringent, but the Daytona
Special met them. The cylinder head was shrouded, there were extra linkages and
hoses around the 28mm Mikuni carburetors (which were mounted on a very
intricate aluminum casting), and a short cast iron exhaust manifold sprouted
between the cylinder head and the exhaust headers.

All this extra equipment was intended to deal effectively
with the unburned hydrocarbons that spew from standard 2-strokes at low rpm,
especially during deceleration. The exhaust manifold contained vacuum-operated
butterfly valves that were open during acceleration and normal running but
closed and mostly blocked the exhaust when the throttle was shut, significantly
reducing the flow of unburned hydrocarbons into the exhaust stream. All this
made the Daytona Special run hotter, but the shrouded cylinder head effectively
aided cooling, and quieted the engine, as well. Changes to the porting improved
the midrange and made scavenging more efficient, and the Daytona got a mild
bump in compression.

Contemporary testers praised the Daytona Special for being
much easier to ride than prior RDs, with a wider powerband that started at just
over 3,500rpm and pulled strongly up to 7,500rpm.

Other improvements included a larger gas tank, lower seat
height and an additional half inch of suspension travel. The footpegs now
bolted above the exhaust system instead of below for improved cornering
clearance. All these improvements came at a price: The RD400F was no longer a
bargain pocket rocket. In fact, it cost about as much as a comparable-sized
4-stroke, listing at $1,694. And that one fact might have been what killed it,
as 1979 was the last year for the RD400.

The conventional wisdom holds that Environmental Protection
Agency mandates killed the U.S.
market for 2-strokes, but it has been suggested that the manufacturers could
have made 2-strokes EPA compliant if they had really wanted to. That might be
true, but it’s also been suggested that it was cheaper and easier to make EPA
compliant 4-strokes instead of EPA compliant 2-strokes. Throw in the fact that
riders were increasingly turning away from 2-strokes for more civilized 4-strokes
and the writing was on the wall.

Two-strokes return

Two-stoke enthusiasts jeered at Yamaha, swore at the EPA and
kept riding their anti-social, noisy and fun motorcycles. At some point about
10 years ago, the remaining 2-stroke enthusiasts realized that their noisy
anti-social bikes had become collectible classics.

One of these enthusiasts was Zeki Abed, whose bikes have
graced these pages before, and he says this is the bike that got him into
collecting. “I almost bought one when I was in college in 1980. I was poking
around on eBay one evening and seeing this bike brought back that memory. It’s
the most refined of all the RDs,” Zeki says.

Most RD400Fs were thoroughly thrashed by owners trying — but
not succeeding — to be Kenny Roberts, but this bike was in mint condition, with
only 554 miles on it. It got Zeki infected with the collecting bug, and he now
has a medium-sized collection of mostly Japanese motorcycles from the
Seventies.

“The Yamaha RD400F Daytona Special is much smoother than previous RD400s,” Zeki
says, “and compared to the 350s, which would wheelie at the drop of a clutch,
the 400 is heavier and more civilized. It will cruise at 70mph without beating
you up. Even though the engine can be a little peaky, it’s more refined.
There’s no premix, no problems idling in traffic, and the brakes are good. With
the footpegs above the mufflers, the ground clearance was better than it used
to be. With the lower seat, the bike lost its ‘sitting on top of the world’
feeling. It feels sportier than previous RDs, with an improved midrange.”

He’s kept the bike’s mileage low, amassing only a slim 400
miles since purchase, but not because he doesn’t enjoy it.

“It’s the favorite bike of all the bikes I have. It reminds
me of a simpler time,” Zeki says. “Not only that, it’s fast and light. It will
embarrass owners of bigger bikes. The word that comes to me to describe the
Daytona is ‘nimble.’ The RD400F gets me back to the bikes of my youth. It’s the
jewel of my collection.”

Dain Gingerelli shares Zeki’s enthusiasm for the Daytona.
“When I was at the original Cycle Guide, we had a project in 1979 about
box stock racing. We raced the RD400F, Honda 400 Hawk and Suzuki GS400. I was
only able to compete in Southern Chapter races, but still finished the season
fifth in points. Nothing was ever replaced on it, other than plugs, oil and
those K81s,” a reference to the Dunlop tires they ran.

Unfortunately, nothing ever replaced the Yamaha RD400F Daytona
Special. Yamaha tried the 2-stroke route one more time after dropping the RD in
1979, offering the sophisticated and water-cooled RZ350 for 1984 and 1985, but
quickly gave up on the idea. The Daytona was the end of the line for air-cooled 2-strokes in the U.S. MC

Share your thoughts.

ROGER SWARTOUT

7/10/2013 4:26:28 PM

This is an interesting story about the RD400 Daytona but it has several errors. The horsepower is 43 at 7500 rpm and it is not the end of road legal air cooled 2-storkes in the US. Kawasaki sold the air cooled, oil injected, kick start KE100 until 2001 and Yamaha sold road legal small air cooled 2-stokes in the 80s and 90s.
I am a fan of the 2-stroke stories as I ride a 1976 Kawasaki KH500 and 1971 Kawasaki A7SS on the street and all of my dirt and road race bikes are 2-stroke.

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